The invention relates to a method for the production of resistant covering elements for building surfaces or the like, especially for the production of decorative floor covering elements, consisting of several layers which are assembled in a sandwich-type construction by applying pressure and heat, with an upper transparent face sheet on the decorative side, which is also referred to as xe2x80x9coverlay paperxe2x80x9d, a decorative layer, a support plate and a lower face sheet, where the upper face sheet is prefabricated from a support layer, in which an abrasion-resistant material is embedded and which is provided with a bonding material, and a covering element manufactured according to this method, consisting of a support plate, a transparent face sheet on the visible side, a decorative layer and a lower face sheet with a tension layer provided on the bottom side of the support plate facing the building surface.
In the previously known covering elements of the type described, four different layers are prefabricated and then bonded together in a sandwich-type construction by applying pressure and heat.
The support layer of the upper face sheet of known covering elements essentially consists of cellulose. The abrasion-resistant material is embedded in the cellulose layer in the form of corundum particles.
According to the known method, the decorative layer is applied to a special layer, which has to be prefabricated for the sole purpose of applying the decorative layer. This layer consists of at least three layers. The first layer is a special white decorative support layer made of paper or the like. The decorative layer, which preferably consists of ink, is applied to this layer by a printing process, for example. A bonding material is then applied to the connected layersxe2x80x94meaning the decorative support layer and the decorative layerxe2x80x94at least on their common top side, preferably on their top and bottom side. Melamine resin, or an agent containing melamine resin, is used as the bonding material, for example.
Thus, the layer containing the decorative layer was previously constructed from four layers in the following order: a top bonding material layer, the decorative layer, the decorative support layer and a bottom bonding material layer.
Manufacturers of covering elements usually produce the support plate themselves and purchase the overlay paper, the special layer with the decorative layer and the lower face sheet from suppliers. The suppliers manufacture the decorative layer in the desired designs.
A covering element can be used until the upper transparent face sheet wears off and is destroyed by the further use of the decorative layer. One disadvantage of the known covering element is that only the bonding material layer on top of the decorative layer contributes to increasing the abrasion-resistance of the covering element. The decorative support layer itself makes no contribution in this context.
Under the influence of pressure and temperature during manufacture, the decorative support layer located on the visible side of the support plate and the support layer of the upper transparent face sheet build up internal stresses acting in the same direction. These stresses cause the covering to deform, primarily in its longitudinal direction, where the line of deformation is perpendicular to the plane in which the covering element extends. The lower face sheet is applied to the bottom of the support plate in order to compensate for the deformation. This sheet has a tension layer. The tension layer also develops internal stresses and counteracts the deformation. The tension layer must develop internal stresses equal in magnitude to those of the layers located on the visible side of the support plate, so that the internal stresses can be counteracted and there is no deformation of the support plate and thus of the covering element.
The tension layer must be able to develop internal stresses equal in magnitude to those of the decorative support layer located on the visible side of the support plate and the support layer together. Assuming that the decorative support layer, the support layer and the tension layer all have roughly the same material quality, the tension layer must be equally as thick as the sum of the thickness of the decorative support layer and the support layer. Therefore, the tension layer requires a lot of material and increases the weight. These factors increase the manufacturing, storage and transport costs of the covering element.
The object of the invention is to design a covering element, and a method of producing it, with which thin, lightweight covering elements can be manufactured simply and the cost of material, manufacturing, storage and transport reduced.
According to the invention, the object is solved in that the decorative layer is applied to the support plate, or in the area of the bottom of the face sheet, and is processed together with the support plate or the face sheet to form a prefabricated layer. In the covering element manufactured according to this method, only the decorative layer and a bonding material layer are located between the support layer of the upper face sheet and the support plate. The thickness of the tension layer of the lower face sheet is essentially equal to the thickness of the support layer.
This simple measure reduces the number of layers to be prefabricated to a maximum of three. The special layer for the decorative layer is eliminated. Instead, it is combined with the upper transparent face sheet to form a single layer. Alternatively, it can also be combined with the support plate to form a single layer. In the latter case, the decorative layer is applied to the top side of the support plate facing the upper face sheet.
Decreasing the number of layers to be prefabricated reduces the number of required manufacturing steps and cuts the manufacturing costs.
The overall thickness of the covering element can be thinner and the covering element can be lighter than before, thus reducing the material, storage and transport costs.
On the visible side of the covering element, the support plate now has only one layer which generates internal stresses, namely the support layer of the upper face sheet. Thus, the tension layer of the lower face sheet can advantageously be thinner than before, meaning essentially as thick as the support layer of the upper face sheet.
If the overall thickness of the known covering element can be retained, the covering element manufactured according to the new method offers another advantage: the support layer of the upper face sheet can then be designed with a thickness equal to the previous thickness of the support layer and the decorative support layer together. This advantageously results in a layer of abrasion-resistant material that is twice as thick and which lasts twice as long as the known covering element under the same degree of wear and tear. In this context, the thickness of the tension layer of the lower face sheet is equal to the thickness of the doubled support layer.
Of course, surfaces other than building surfaces, such as furniture surfaces, can be advantageously manufactured according to this method. It is particularly suitable for, among other things, kitchen counters, which need to have an especially durable surface.
The decorative layer is expediently manufactured by coating with ink. It is particularly favourable if the decorative layer is applied to the bottom of the support layer of the face sheet. Alternatively, a bonding material layer can first be applied to the bottom of the support layer of the face sheet, followed by the decorative layer. The face sheet prefabricated in this way can then be prefabricated by the manufacturers of overlay papers and purchased and further processed by the manufacturers of the covering elements.
For reasons relating to the technical manufacturing process, it can be advantageous to apply the decorative layer to the top of the support plate. It then comes into contact with the bonding material at a later time.
The ink for the decorative layer is preferably applied according to the known printing process.
An example of the present invention is described below based on the drawings. The drawings show the following: